Breviary Technical Ceramics






7.5.2 Ways to Improve Loading Capacity

  • Constructive design
    o compressive stress is preferable in ceramic parts and can be achieved through appropriate
       - specification of how the load is applied,
       - part design,
       - the positioning of joints and contact points
    o creating compressive pre-stress to compensate for tensile stresses during use, for example by
       - casting metal around the ceramic,
       - shrink-on bushings/sleeves on rotationally symmetrical ceramic parts,
       - pre-stressing when assembled,
       - technological measures (e.g. glazing high tension insulators).
    o increasing the loading area, avoiding stress concentrations,
    o dividing large-volume parts into several pieces (modular construction). consideration of the effect of volume on the strength, in particular if the Weibull modulus m < 20.

  • Choosing a different material
    o using a material with higher strength,
    o using a material with greater KIC-value (greater crack resistance),
    o using dispersion-strengthened material (e.g. aluminium oxide reinforced with zirconium oxide),
    o using fibre-reinforced materials.

  • Technological measures
    o machining only in a direction parallel to the direction of maximum stress,
    o creating compressive stress in the surface region,
    o controlling and exploiting transformation processes in the crystal structure, especially when using zirconium oxide.


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